The present invention relates to a sheet processing apparatus, a sheet processing system, and a sheet processing method for processing sheets such as stapling sheets, punching sheets, and folding sheets, and relates to the sheet processing apparatus, the sheet processing system, and the sheet processing method which are independent as a sheet processing apparatus, are integrated into a sheet output apparatus such as a copying machine, a printer, a facsimile, or a printing press, or are attachingly installed on a sheet output apparatus for realizing individual features such as stapling, punching, and folding.
Conventionally, different types of sheet processing apparatuses for stapling, punching for filing, and folding after stapling sheets on which images are recorded with an image forming apparatus such as a copying machine, a printer or a facsimile have been proposed.
As Japanese Patent Laid-open No. Hei 10-279163 and Hei 11-193162 disclose, sheet processing apparatuses having features of stapling and folding multiple sheets at the center have been well known. These sheet processing apparatuses are constituted in such a manner that they staple a sheet bundle at the center in a conveying direction for example, then fold the sheet bundle into two at the center in conveying direction, and discharge sheet folded at the center on a stacking tray with discharging rollers.
This type of sheet processing apparatus with a simple book binding feature (sheet post-processing apparatus), which staples a sheet bundle at the center and folds the sheet bundle into two, stacks a sheet bundle folded into two on a tray in such a manner that a part where the sheet bundle is stapled and folded faces toward a sheet conveying direction, or, in other words, the part where the sheet bundle is stapled and folded is placed on a farther side from a main unit of the sheet post-processing apparatus when the sheet post-processing apparatus staples a sheet bundle at the center, and discharges and stacks the sheet bundle folded into two. When the sheet bundle stapled and folded at the center is stacked in such a manner that the part stapled and folded at the center is placed on the farther side from the main unit of sheet post-processing apparatus, both ends of the sheet bundle, which are not folded, bulge.
Though the tray is generally tilted upward on the downstream side of sheet discharging direction, as the number of stacked sheet bundles increases, the both ends of sheet bundle, which are not folded, bulge, a volume on a side of the sheet bundle, which is generally lower, increases, and a sheet bundle stacking face on the downstream side of sheet discharging direction becomes lower.
When a sheet bundle is discharged on the sheet bundle stacking face in the state tiled downward on the front side, the sheet bundle falls down from the sheet bundle stacking face, and is not stacked on the stacking tray properly. To avoid this problem, it is required to limit the stacked amount. When the stacked amount is limited in this way, the image forming is suspended at a processed number of sheets corresponding to that stacked amount, leading to a decrease of the processing efficiency. Since the amount of bulge depends on the thickness, the number, or the flexibility of a sheet bundle to be folded into two, even if the stacked number is limited, a sheet bundle may not be stacked on the tray.
When the tray is placed horizontally in a conventional apparatus, the tendency of tilting downward on the front side increases, and the stacked amount is decreased accordingly. To avoid this problem, a sheet pressing arm, which has a fulcrum on an upper side of a sheet discharging opening, and presses a sheet bundle at a free end, is provided.
However, with this type of sheet pressing arm, an area to be pressed is limited by a relationship between length of the arm and an installed position of the arm, and the stacked amount of sheets does not increase largely.
Also, since a contact with a top face of sheet bundles is close to a point contact or a line contact, the sheet bundles are not pressed sufficiently, and the bundles are stacked while they are in bulged state. Thus the stacked amount of sheet bundles is limited.
Also, a conventional example is provided with a dedicated stacking tray for stacking sheet bundles which are stapled at the center and then folded into two. Also a dedicated slope for this tray (such as horizontal slope) is set and fixed. Providing this type of dedicated tray increases the complexity of mechanism of the entire sheet post-processing apparatus, and it is not avoidable that the cost increases accordingly. A space for installing a dedicated tray is also required, thereby increasing the entire size of apparatus, resulting in never meeting a requirement of space saving and downsizing.
As shown in FIG. 36, when a pair of rollers 451 and 452 discharge a sheet bundle 700 in such a manner that a front end F on a folded side faces the a stacking tray 301 whose downstream side in a sheet discharging direction tilts upward after the sheet bundle is stapled and folded at the center, the position of a bulged part depends on the size of sheet bundle 700, the stacked states are not aligned depending on where the bulged part is generated on the sheet bundle 700, the stacked state also becomes unstable in this case, and an incident that the sheet bundle 700 falls from the stacking tray 301 occurs. Thus, the stacked amount does not increase.
The present invention is made in view of these problems, and the purpose is to provide a sheet processing apparatus stacking more sheet bundles which are stapled at the center and folded into two.
An alternative purpose of the present invention is to provide a sheet processing apparatus whose sheet discharging tray is shared by standard sheets which are not folded into two.
Another alternative purpose of the present invention is to provide a sheet processing apparatus which stacks sheet bundles folded into two without increasing the size of apparatus.
Another alternative purpose of the present invention is to provide an image forming system comprising this type of sheet processing apparatus and an image forming apparatus.
Another alternative purpose of the present invention is to provide a sheet processing method which stacks more sheet bundles stapled at the center and folded into two.
To attain the purposes described before, the present invention provides a sheet processing apparatus comprising a center-stapling mean for stapling the center of a sheet bundle conveyed from a sheet output apparatus, a center-folding mean for folding the stapled sheet bundle into two, a discharging mean for discharging the sheet bundle folded into two in such a manner that the side folded into two is discharged first, a turning-over mean for turning over a sheet bundle discharged from the discharging mean so that the side folded at the center is oriented to upstream side in sheet conveying direction, and a stacking tray for stacking a sheet or sheet bundle discharged from the discharging mean and turned over by the turning over mean.
The turning-over mean comprises a guide plate for forcing the front side of a sheet bundle discharged from the discharging mean orient downward for discharging. The guide plate is urged toward a closing direction with a predetermined force, and the maximum opening of guide plate is set to a predetermined angle. The guide plate is closed, and retracts to or beyond a face flush with a rear end fence with which a rear end side of a sheet bundle is in contact for a standard discharging without folding a sheet bundle into two, thereby eliminating an interference when the sheet stacking tray moves up/down. It is preferable to provide a detecting mean for detecting an open/closed state of the guide plate.
The turning-over mean may comprise a mean for changing an angle of the stacking tray in such a manner that the angle of stacking tray is steeper than that for the standard discharging without folding a sheet bundle into two. In this state, the angle changing mean changes an angle of the stacking tray more than a angle sufficient for generating a slide in a downward direction of the front end on the side folded into two of a discharged bundle when the front end of sheet bundle comes in contact with the stacking tray or a top sheet face of stacked sheet bundles. The angle changing mean may change only a part of the stacking tray. When the angle changing mean is constituted in such a manner that the angle of only a part of the stacking tray is changed, an auxiliary tray, which rises from the stacking tray with a predetermined position on the stacking tray as a fulcrum, provides this constitution. It is preferable to set the predetermined position in a range of 40 mm 10 mm from the rear end fence. The mean for rising the auxiliary tray is constituted with a cam mean, which operates according to the position of stacking tray.
A sheet processing apparatus is provided with a lifting mean for lifting up/down the stacking tray, and a stacking tray driving control mean for controlling drive of the lifting mean, the stacking tray driving control mean moves the stacking tray from a standard discharging position for standard discharging without folding a sheet bundle into two to a predetermined lower position, and operates the cam mean to raise the auxiliary tray when a mode for discharging a sheet bundle folded into two is set. A lock mean for locking a position of an auxiliary tray when the auxiliary tray raises is provided. It is necessary that the lock mean is released when the stacking tray moves up from the predetermined position. The auxiliary tray is constituted in such a manner that it does not rise due to a self-weight of sheets when the stacking tray moves to the predetermined lower position for standard discharging without folding sheet bundles into two.
For the turning-over, the discharging mean is constituted with a pair of discharging rollers, and the peripheral speed of an upper side roller of the discharging rollers is higher than the peripheral speed of a lower side roller. For this constitution, a driving control mean for driving the pair of rollers is introduced as the turning-over mean.
The present invention also provides a sheet processing apparatus comprising a center-stapling mean for stapling the center of a sheet bundle conveyed from a sheet output apparatus, a center-folding mean for folding the stapled sheet bundle into two, a discharging mean for discharging the sheet bundle folded into two in such a manner that the side folded into two is discharged first, a stacking tray for stacking a sheet or sheet bundle discharged from the discharging mean, a lifting mean for lifting the stacking tray, a stacking tray driving control mean for controlling drive of the lifting mean, and moving the stacking tray from a standard discharging position for discharging without folding a sheet bundle into two to a predetermined lower position shorter than a conveying distance of a folded sheet bundle when a mode for discharging a sheet bundle folded into two is set, and a guide mean for deflecting downward the front end of sheet bundle discharged from the discharging mean, the guide mean makes the front end folded into two of the sheet bundle come in contact with the stacking tray or a top sheet face of stacked sheet bundles, and the discharging mean maintains the discharging operation in this state to turn over the sheet bundle, thereby stacking the sheet bundles on the sheet upper side stacking tray.
When the front end of side folded into two of a sheet bundle comes in contact with the stacking tray or a top sheet face of stacked sheet bundles, a pushing member, which pushes a part at least closer to the rear end than to the front end, pushes out a non-stapled side toward the downstream side in discharging direction may be provided to turn over the sheet bundle surely.
The present invention provides a sheet processing apparatus comprising a center-stapling mean for stapling the center of a sheet bundle conveyed from a sheet output apparatus, a center-folding mean for folding the sheet bundle into two, a discharging mean for discharging the stapled and folded sheet bundle, a stacking tray for stacking a sheet or sheet bundle discharged from the discharging mean, an aligning mean for aligning the sheet bundle on the upstream side in a discharging direction of the stacking tray, and a pressing mean for pressing the sheet bundles stacked on the stacking tray on the aligned end.
The aligning mean aligns the sheet or sheet bundle on the folded side of sheet or sheet bundle. The aligning mean comprises the stacking tray tilted in such a manner that the downstream side is higher than the upstream side in a conveying direction, and a rear end fence which supports the stacking tray for lifting up/down, and ends of the sheet bundles discharged on the stacking tray are in contact with. The folded side of sheet bundle folded into two is discharged first to align the sheet bundles on the folded side, and a turning-over mean is provided to turn over the sheet bundle in such a manner that the folded side is positioned on a side of the aligning mean.
The pressing mean comprises a pressing member, which comes in contact with a top face of a sheet bundle, and a driving mean for protruding and retracting the pressing member from a contact face of the rear end fence with which the aligned ends of sheet bundles come in contact, for example. The protruding/retracting action of pressing member is linear. Or, the action may not be linear, and the pressing member operates in such a manner that the pressing member is protruded at an upward angle to the sheet stacking face of stacking tray, and a downward angle to the sheet stacking face of stacking tray is maintained when the pressing member is fully protruded. The action is inversed when the pressing member is retracting.
The sheet processing apparatus is provided with a lifting mean for lifting the stacking tray, and the lifting mean lifts up the stacking tray while the pressing member is protruded over the sheet bundles placed on the stacking tray, thereby pressing the sheet bundles between the pressing member and the stacking tray to restrain the bulge of sheet bundles. This reduces the volume of sheet bundles when a large number of them are stacked, thereby stacking larger number of them.
A detecting mean for detecting a pressing force for pressing the sheet bundles is provided, and the lifting mean stops a lifting-up action when the detecting mean detects that the pressing force is more than a predetermined value. This allows always pressing the sheet bundle at a constant pressing force. For pressing securely, an angle between a protruding direction of the pressing member and the stacking face of stacking tray is set as:
xcex8fxe2x89xa7xcex8t
where xcex8f is an angle between the pressing member and the rear end fence (on the sheet discharging side), and xcex8t is an angle between the stacking tray and the rear end fence (on the sheet discharging side) when the lifting mean stops the lifting-up action of stacking tray. This setting prevents the sheet bundles from displacing, and securely presses the sheet bundles even if the stapled side bulges.
An example of the detecting mean comprises an urging member for urging a member for supporting the pressing member in a direction resisting against the lifting-up action of the lifting mean, and a position detecting mean for detecting the position of the supporting member, and detects whether the pressing force is more than the predetermine value or not from a position of the supporting member detected by the position detecting mean.
The discharge of sheet bundle is conducted by the discharging mean while the pressing member is being protruded, the discharging mean discharge the sheet bundle, the sheet is stacked on a top face of the pressing member, and then the driving mean retracts the pressing member inside the rear end fence. After the pressing member retracts, the lifting mean lifts down the stacking tray a predetermined distance. The predetermined distance is set variably according to the stapled sheet number of the sheet bundle.
As the turning-over mean, an angle changing mean, which changes an angle of the stacking tray in such a manner that the angle of stacking tray is steeper than that for the standard discharging without folding into two, is introduced. As the angle changing mean, an auxiliary tray, which rises from the stacking tray with a predetermined position of the stacking tray as a fulcrum is used. The predetermined position is provided in a range of 40 mm 10 mm from the rear end fence, or, in other words, a lower end of sheet stacking face of the stacking tray considering the sizes of sheets which are commonly used such as A4, letter size and legal size. It is desirable that the protruding amount when the pressing member protrudes, is set to a distance from the rear end fence (lower end of the sheet stacking face of stacking tray) to the angle changing position of stacking tray, or, in other words, a distance approximately equivalent to that to the fulcrum of the auxiliary tray. The protruding amount when the pressing member protrudes is set in such a manner that it decreases as the stack number of sheet bundle stacked on the stacking tray increases, or is variable according to stapled number of sheets.
If the pressing member is set to a dimension for pressing a predetermined area set symmetrical about the center of sheet bundle (dimension for pressing a predetermined length orthogonal to the sheet conveying direction), the pressing member provides a secure pressing. Independent multiple pressing members may be provided in positions symmetrical about the center of sheet bundle for simplicity. It is important to press positions symmetrical about the center. Otherwise, the stack state becomes unstable, and the stack amount does not increase.
For the pressing member, coefficient of friction on the top face is set higher than that on the bottom face so as not to displace the position of sheet bundles during the protruding/retracting acting. To attain the same concept, a roller, which is set rotational at least when the pressing member is protruding may be provided at tip of the pressing member.
The present invention provides a sheet processing system comprising the sheet processing apparatus of individual forms of the present invention described before, an image forming apparatus including an image forming mean for forming an image based on an entered image data, and an input mean allowing a user to select at least stapling mode for stapling a sheet bundle at the center, and folding mode for folding a sheet bundle into two at the center, a first controlling mean for controlling individual parts of the sheet processing apparatus, and a second controlling mean for mutually communicating with the first controlling mean, sending control information to the first controlling mean, and controlling individual parts of the image forming apparatus, and the sheet processing apparatus uses the turning-over mean set for the sheet processing apparatus to turn the sheet bundle to stack on the sheet stacking tray when both the stapling mode and the folding mode are set from the image forming apparatus.
The present invention provides a sheet processing system comprising the sheet processing apparatus of individual forms of the present invention described before, an image forming apparatus including an image forming mean for forming an image based on an entered image data, and an input mean allowing a user to select at least stapling mode for stapling a sheet bundle at the center, and folding mode for folding a sheet bundle into two at the center, a first controlling mean for controlling individual parts of the sheet processing apparatus, and a second controlling mean for mutually communicating with the first controlling mean, sending control information to the first controlling mean, and controlling individual parts of the image forming apparatus, the sheet processing system applies a process on a sheet bundle discharged from the image forming apparatus, the sheet processing apparatus lifts down a stacking tray for stacking the discharged sheet bundle to a predetermined position lower than a position where a pressing plate is provided for pressing the sheet bundles stacked on the stacking tray on an aligned end when both the stapling mode and the folding mode are set from the image forming apparatus, uses a turning-over mean to turn over the sheet bundle, and to stack the sheet bundle on the stacking tray, and uses the pressing plate and the stacking tray to press the sheet bundles on a stapled side.
The present invention provides a sheet processing method which folds a sheet bundle stapled at the center of sheets into two at the same center, stacks the sheet bundle on a predetermined stacking tray, and comprises steps of folding the sheet bundle into two at the center, restricting dropping direction of the sheet bundle to a predetermined direction, setting a tilting angle of the stacking tray so that a front end on the folded side of dropped sheet bundle is placed on the lower side of tilted stacking tray, turning over the sheet bundle, and stacking the sheet bundle on the stacking tray.
The present invention provides a sheet processing method for attaining the purpose described before which folds a sheet bundle stapled at the center of sheets into two at the same center, stacks the sheet bundle on a predetermined stacking tray, and comprises steps of folding a sheet bundle into two at the center, turning over the sheet bundle, aligning the sheet bundle on a stapled side, protruding a pressing plate over aligned sheet bundles, lifting up the stacking tray while pressing a top face of the sheet bundles with the pressing plate, applying a predetermined pressing force between the pressing plate and the stacking tray to restrain a bulge of the sheet bundles, and stacking aligned sheet bundles on a stacking tray.
These individual constitutions provide sheet processing apparatuses for stacking larger number of sheet bundles stapled and folded into two at the center. Since a discharge tray for standard sheets which are not folded into two is also applied to this apparatus, the sheet bundles folded into two are stacked without increasing the size.